Oil return device for flooded evaporators



May 26, 1936. J. ASKIN ET AL OIL RETURN DEVICE FOR FLOODED EVAPORATORS Filed Nov. 3, 1933 FIG, I.

Snnentors JOSEPH D. LEAR at onieg create in the suction Patented May 26, 1936 UNITED STATES OII RETURN DEVICE FOR ELOODED EVAPORATORS.

Joseph" Askin and Joseph D. Lear, Buffalo, N. Y.,

assignors to Fedders Inc., Buffalo, N. Y.

Manufacturing Company,

Application November 3, 1933, Serial No. 696,521

7 Claims.

This invention relates to oil recovery devices for mechanical refrigeration systems of the flooded type, and it has particular reference to means separated in the evaporator.

In the usual header or boiler forming a part of a flooded type refrigeration system, oil separates from liquid refrigerant and its accumulation presents a problem of removal and, return to the evaporator. According to the present invention, the return of separated oil is effected by means of a siphon wick, which is advantageously disposed in a suction tube connected to the compressor. In applying theinvention in practical forms, the opening of the suction tube is also utilized to effect the return of gasified refrigerant, and provision is made to prevent the splashing of liquid refrigerant into such tube, without however, so decreasing the lifting power of the wick or siphon as to interfere adversely with itsoil lifting function.

In the embodiments of the invention hereinafter described'provision is also made to guard or shield the wick from liquidl'refriger antfand to tube a partial pressure reduction, whereby the draining of the wick will be facilitated,features which may be advane tageously included in the application'of the principles just above outlined.

In another aspect, the. invention provides a gasified refrigerant and liquid. lubricant return device, in which the parts while assembled in unitary relationship, provide for the return ofv refrigerant gas at a high or dry point of the evaporator, and the return of lubricant separated from the refrigerant at a wetor low point, so that the oil wick need lift the oilthrough only a limited distance.

The invention will be found to provide a. relatively simple and inexpensive. structure which is particularly devised for the space and production problems of the modern header, as more specifically described in the accompanying specification and drawing, wherein:

Fig. 1 is a longitudinal section through a header containing an oil return device forming the first embodiment of theinvention;

Fig. 2 is a longitudinal section through a similar header containing an oil; return device forming thesecond embodiment of the invention; 2

Fig. 3 is a perspectiveview showing thewick siphon of Fig. 1 on an enlarged scale; a wall of the wick is broken away; to show the; cross section thereof.

The drawing illustrates several embodiments of the invention, each of which is devised to be mounted within an expansion chamber or header l0, forming partof the evaporator of 'a refrigeration system of the well known flooded 5 type. The header I 0 may be formed in the usual manner, including a shell I I and a head plate l2 united by a soldered joint l3 to form a closed body. Refrigerant is introduced into the header through an input fitting l4 secured to the plate I2 and a communicating passage l5. A valve l6 controls the flow through this passage, and it is controlled by a float l'l pivoted to the plate l2, and cooperating to maintain a predetermined liquid level in the header, as indicated by the numeral i8. Gasified refrigerant is withdrawn from the header through a suction conduit l9rwhich communicates therewith through a fitting 2| secured to the plate I2.

Asthus far described, the header structure presents a well known device wherein a refrigerantoil solution is subjected to expansion and the eventual releasing of the oil volumes to form an oil layer 22 at the liquid level I8. The oil-refrigerant ratio varies to a considerable degree in 2 5 diiferent refrigeration systems, chiefly in accordance with the lubrication demands of the. type of compressor utilized, and in order to disclose the flexibility of the oil return device which forms the present invention, the embodiment thereof as shown in Fig. 1 is devised for a slow rate of oil return, while that of Fig. 2, although similar in principle'of operation, is devised for a relatively faster rate of oil return.

In Fig. 1 the oil return device is associated with 3 a suction tube 23 which is secured at one end to the plate l2 in communication with the suction conduit H3. The tube is formed with a loop portion 24 which depends through the oil layer 22 and terminates in a vertical terminal portion 25 v disposed above the liquid level I 8. Oil is withdrawn from the oil layer 22 and conveyed into the terminal portion 25 of the tube 23 by a siphon device 26, which is preferably in the form of a cylindricalwick (Fig.3) consisting of a c ylindrical leg 21 disposed about the exterior ofthe terminal portion 25 and an integral deliveryleg 28 disposed within the terminal portion 25 and having a greater axial length.

'I'heextremity of thewick leg 27 extends into theoil layer 22 where it is operative to withdraw oil bycapillary action for upward disposal tothe delivery leg. 28, whence, due to gravitational ef. fects, itfinally drips from the, extremity of the the header) be considerable degree.

extends from approximately the liquid level to the top of the header, to provide a substantial continuation or'extension of the suction tube.

In actual operation the placid condition of the liquid level l8, which may be inferred from the drawing, is not continuously maintained, as turbulence ranging from a slight wave effect to violent eruption is a frequent occurrence as occasioned by ebullition in response'to physical and thermal shocks in the refrigerator. The close proximity of the tube terminal 25 to the liquid level I8, therefore, incurs the danger of flooding during such periods, and the introduction of liquid refrigerant into the suction line; which danger is obviated by the provision of the tube extension 29 which in effect raises the input end of the suction line to the top of the header and out of the danger zone. The tube extension 29 has the further functions of protecting the wick during such periods; of enclosing the wick leg 21 between its wall and the annular wall of the tube end 25 to increase or improve the capillary action therein; and also in insuring that the warmest gases (which naturally segregate at the top of first directed to the suction conduit. In its latter aspect, the suction tube 23 and the extension tube 29 may be considered a single conduit wherein a wick or wicks are interposed at a point adjacent the liquid level in-the header.

In'Fig. 2, a suction tube 3l, of larger cross sectional area than that of Fig. l, is secured to the plate I2, and it is similarly formed with a depending loop portion 32 terminating in avertical terminal portion 33, extending above the liquid level I8. A siphon wick 34 is mounted over the extremity of the terminal portion and it is similar in disposal to the described wick 26, having an exterior cylindrical leg '35 and an integral interior leg 36. An extension tube 31 is fitted within the interior leg 36 of the wick in light engagement therewith. A shield or skirt member 38 is secured to the exterior of the tube 31 and it is formed with a flared portion 39 which depends downward to encompass all but the lower extremity of the exterior wick leg 35. The extremity 4| of the skirt member may terminate immediately above the liquid level [8 as shown, or it may be spaced at a greater distance from the liquid level.

The operation of the embodiment of the invention shown in Fig. 2 will be found to be similar to that of Fig. 1 during idle or off cycle periods of operation of the refrigeration system. Under this condition the siphon action of the wick 34 will be aided by the walls of the skirt 38 and tube 31 to withdraw oil from the header for delivery into the loop portion 32 until the liquid levels therein and in the header are coincident. Upon resumption of the operation of the compressor the suction head is resumed in the suction line, whereupon any oil deposited in the loop portion 32 is withdrawn.

During the operation of the compressor, the gas drawn through the tube extension 31 and past the lower end thereof will tend to create an area of low pressure about the lower extremity 'of the inner wick leg 36, whereupon the siphoning action of the wick will be supplemented to a As a result, aside from paratively greater than proportionalconsiderations, the oil delivery characteristics of the wick siphon 34 are com- 26 of Fig. 1 during on cycle periods of operation of the refrigeration system.

With regard to the choice of material for the wick siphons, it will be noted. that due to the partial enclosure thereof in the structures described, the danger of detached particles entering the refrigerant system is curtailed to a considerable degree. In view of this, cotton or other textile materials may be used therefor, providing their structure is not subject to deteriorization by the refrigerant. It is preferred, however, to. form the wicks out of fine bronze screening of between 100 and.150 meshand of one or more thicknesses, dependent upon the rate of oil return desired.

It will be obvious from the foregoing that a rigid standard cannot be established in oil return devices, since conditions of operation and lubrication problems vary. with different types of equipment; therefore, it is intended that the described embodiments of the invention be considered as exemplary of structural applications of the general principles set forth, which may be varied within the scope of the following claims.

Weclaim: V

1. In a refrigerating apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and refrigerant body, means for maintaining a substantially constant liquid level in the header below the top thereof, a suction tube mounted within the header and formed with a looped portion depending into the liquid and having its open extremity terminating in close proximity to the top of the header, and a siphon device communicating with the oil layer in the header and entered in said tube at a point below said open extremity thereof and adjacent to'the liquid level. 1 1

2.-In a refrigerating apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header andbeing formed with a looped portion depending into the liquid and having its extremity terminating in close proximity with the top of the header, said suction tube being formed of two parts disposed in telescoped relation at a point adjacent to and above the liquid level, and an oil layer in the header and interposed between the telescoped parts of the suction tube.

3. In a refrigerating apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header and formed of a looped tube depending into the liquid and having its ex-' tremity extending upward and terminating adjacent to and above the oil layer, and an extension tube disposed in telescoping relation with the extremity of the looped tube and extending upward in the header to a point adjacent the top thereof, and an oil return wick entered in the oil layer and interposed between the telescoped parts of the suction tube. 7 4. In a refrigeration apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header and formed of a looped oil return wick entered in the' those of the wick siphon tube depending into the liquid and having its extremity extending upward and terminating adjacent to and above the oil layer, and an extension tube disposed in telescoping relation with the extremity of the looped tube and extending upward in the header to a point adjacent the top thereof, a cylindrical wick having one portion engaged about the exterior of the looped tube and entered in the oil layer and its opposite portion disposed within the looped tube and terminating at a point lower than the liquid level in the header, whereby said wick provides a siphon to withdraw oil from the header for delivery into the looped tube.

5. In a refrigeration apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header and formed of a looped tube depending into the liquid and having its extremity extending upward and terminating adjacent to and above the oil layer, and an extension tube disposed in telescoping relation over the extremity of the looped tube and extending upward to a point adjacent the top of the header, and a cylindrical wick having one portion engaged between the telescoped tubes and entering the oil layer and a remaining portion disposed within the looped tube and terminating at a point lower than the liquid level in the header, whereby said wick provides a siphon to withdraw oil from the header for delivery into the looped tube.

6. In a refrigeration apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header and formed of a looped tube depending into the liquid and having its extremity extending upward and terminating adjacent to and above the oil layer, a cylindrical Wick having one portion engaged about the exterior of the looped tube and entering the oil layer and its opposite portion disposed within the looped tube extremity and terminating at a point lower than the liquid level in the header, and a cylindrical shield enclosing the wick on the interior and exterior of said looped tube extremity.

7. In a refrigerating apparatus comprising a header having an inlet for admitting oil and refrigerant for gravitational separation into an oil layer and a refrigerant body, a suction tube mounted within the header and formed of a looped tube depending into the liquid and having its extremity extending upward and terminating adjacent to and above the oil layer, a cylindrical Wick having one portion engaged about the exterior of the looped tube and entering the oil layer and a remaining portion disposed within the looped tube extremity and terminating at a point lower than the liquid level in the header, and a cylindrical shield enclosing the Wick on the interior and exterior of said looped tube extremity, said shield having a tubular extension disposed vertically in the header and terminating adjacent the top thereof to provide a gas input device.

JOSEPH ASKIN. JOSEPH D. LEAR. 

